Electronic organs have been known in the patent arts and in the marketplace for many years. Such organs heretofore generally operated on analog principles with the provision of one tone generator for each note of the organ. It has been common practice to use separate oscillators for each generator, or to provide twelve master oscillators for the top octave or one octave above the top octave with divide-by-two circuits for producing the remaining octaves of the organ. More recently it has become rather common practice to provide a single high frequency master oscillator and to divide the frequency thereof by parallel dividing circuits of different divider ratios to provide the top octave of notes, such top octave being applied to strings of divide-by-two circuits to provide the gamut of the organ.
More recently efforts have been made to produce electronic organs using digital circuits, including to some extent the elimination or minimization of redundancy in the number of tone generators combined with multiplexing of the keyboards. Digital circuits for electronic organs are relatively easily embodied in large scale integrated circuit (LSI) chips, whereas it is relatively difficult to embody analog circuits in such chips.